Lamp for road vehicles and like purposes



Jufiy 31, 1923.

A. C. WHITEHEAD LAMP FOR ROAD VEHICLES AND LIKE PURPOSES Filed July 18.1922 Patented duly 3i, i923.

ARCHIBALD CHARLES WHITEHEAD, OF IPSWICH, ENGLAND.

LAMP FOR ROAD VEHICLES AND LIKE PURPOSES.

Application filed July 18, 1922. Serial No. 575,784.

To all whom. it m ay concern Be it known that I, Ancnnmnn CHARLESlVHIrnnnAn, of Ipswich, county of Suffolk, England, a subject of theKing of Great Britain and Ireland, have invented certain new and usefulImprovements Relating to Lamps for Road Vehicles and like Purposes, ofwhich the following is a specification.

This invention relates to head lamps for road vehicles.-

Hitherto various methods have been suggested for eliminating thedazzling eflect produced by the head-lights of a road vehicle onapproaching persons.

The principal'object of the present invention is to provide a novel andimproved reflector for such headlights which can be produced by an easymodification of the well known methods of producing reflectors, andwhich will give in use a beam of light of which part is substantiallyhorizontal, and part is directed downward, it being assumed that thereflector is set in a position corresponding with that of the ordinaryreflector.

According to the invention I provide a. head lamp in which, While onepart of the reflecting surface (hereinafter called the regular part) isof the well known form, namely, a paraboloidal surface generated by aparabolic segment rotating about its major axis, the remainder(hereinafter called the deformed part) consists of a surface of whichthe curve is generated by rotating the same parabolic segment about itsmajor axis, the said axis tilting progressively in position duringrotation of the gencrating curve, and the tilting taking place about apoint displaced longitudinally of the optical axis of the regular partfrom the focus of such part.

With the above and other objects in view as will be hereinafterapparent, the invention consists in general of certain novel details ofconstruction and combinations of parts hereinafter more fully described,illustrated in the accompanying drawin s, and specifically claimed.

In the accompanying drawings like char: acters of reference indicatelike parts in the several views, and:

Fig. 1 is a front view of a reflector constructed in accordance withthis invention.

Fig. 2 is a longitudinal vertical section therethrough.

In these drawings, a indicates the regular part of the reflector havinga fixed optical axis 6 while 0 is a deformed part or part having an axisthat varies between the position of the axis 1) and the axis (1, itbeing noted that the variable axis tilts about a point 32' positionedrearwardly of the focus p of the regular part. a. The curve 9 shows theposition in which the reflector would lie if the same was not deformed,and g is approximately the position of the inner end of an electricfilament or source of light.

The manner of forming'the reflector is as follows:

The lower half of the reflector is generated by a parabolic arc revolvedfrom a horizontal position about its major axis through 180. The upperhalf of the reflector is generated by continuing the revolution of thissame parabolic are through the remaining 180, the arc being displacedbackward so that the focus is moved to the rear of the focus of thelower half, the cen-' ter of illumination still remaining in rear of thefocus of the upper half, and simultaneously with the movement ofrevolution tilting the axis downward at its front end, the downwardtilting being at a minimum, namely Zero, at the beginning of itsrevolution, lncreasing to a maximum when the arc has been moved throughand then decreasing to the minimum during the movement back tohorizontal. By means of this operation, the lower half of the reflectorwill produce a normal reflection, and since the center of illuminationis in rear of the focus, the rays reflected from said lower half will beinclined downwardly. In like manner, the downward tilting of the axis ofthe upper half of the reflector forms this upper half into a species ofoblate paraboloid, and by the proper proportioning of the angulardisplacement of the axis in relation to:

the movement of the parabolic are thereabout, the rays reflected fromthis upper half and emanating from the light source will at no time bedeflected upwards.

It is obvious that mechanically such a construction may be produced byspinning on a form, pressing, or any variety of other we s.

t will be seen from the foregoing, that the downward tilting of the;axis of the deformed part of the reflector directs the light 4 rays fromthe focus p in a. downward beam, the particular distribution of which isregulated by the extent of displacement between the points 3? and 3) andthe angle between the axes b and d. i

A reflector constructed in this manner ensures distribution of lightwhich with proper positioning of the axis 7) in relation to a horizontalline, a distribution of the lightin such manner that the road will bewell lit, while at the same time there will be no glare in the eyes of aperson approaching the \ehicle. or being approached by it.

There has thus been provided 21 simple and e'flicient device of the kinddescribed and for the purpose specified.

Having thus described the inventioinwhat is claimed is new, is:

A reflector of the class described consisteas es ing of upper and lowerhalves, the lower half having a reflecting surface of regularpurziboloidal form, the upper half having a reflecting surt'ai-egenerated by the revolution of a parabolic segment about the major axisof the segment and simultaneously with said revolution tilting saidmajor axis downwardly about a point displaced longitudinally of the axisof the lower half rear- Wardly from its focal point whereby the upperdeformed half of the reflector is hodily displaced with reference to thelower regular half.

In testimony whereof I have signed my name to this specification.

ARCHKBALD \CHARLES Wldl'll'lilililll).

